Image sensor

ABSTRACT

An image sensor includes an insulating pattern disposed on a semiconductor substrate and having an opening, a color filter disposed within the opening of the insulating pattern, a capping insulating layer disposed on the color filter, a first electrode disposed on the capping insulating layer and having a portion overlapping with the color filter, a separation structure surrounding a side surface of the first electrode, and a photoelectric layer disposed on the first electrode. The separation structure includes a first insulating layer and a second insulating layer formed of different material.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/851,763, filed on Dec. 22, 2017, which claims the benefit of KoreanPatent Application No. 10-2017-0092476, filed on Jul. 21, 2017, in theKorean Intellectual Property Office, and the entire contents of eachabove-identified application are incorporated by reference herein.

BACKGROUND 1. Technical Field

The present inventive concept relates to an image sensor, and moreparticularly, to an image sensor including an electrode and a method offorming the same.

2. Description of Related Art

Image sensors capturing images and converting images into electricalsignals have been used in cameras mounted in automobiles, securitydevices, and robots, as well as consumer electronics, such as digitalcameras, cameras for mobile phones, and portable camcorders. These imagesensors have required compact size and high resolution.

SUMMARY

According to an aspect of the present inventive concept, an image sensoris provided. The image sensor includes an insulating pattern disposed ona semiconductor substrate and having an opening, a color filter disposedin the opening of the insulating pattern, a capping insulating layerdisposed on the color filter, a first electrode disposed on the cappinginsulating layer and having a portion thereof overlapping the colorfilter, a separation structure surrounding a side surface of the firstelectrode, and a photoelectric layer disposed on the first electrode.The separation structure may include a first insulating layer and asecond insulating layer formed of different materials.

According to an aspect of the present inventive concept, an image sensoris provided. The image sensor includes an insulating pattern disposed ona semiconductor substrate and having an opening, a color filter disposedin the opening of the insulating pattern, a capping insulating layerdisposed on the color filter, an electrode disposed on the cappinginsulating layer, a separation structure surrounding a side surface ofthe electrode, and a photoelectric layer disposed on the electrode andthe separation structure. The separation structure has an upper surfacerecessed in a direction toward the semiconductor substrate.

According to an aspect of the present inventive concept, an image sensoris provided. The image sensor includes an insulating pattern disposed ona semiconductor substrate and having a first opening, a color filterdisposed in the first opening of the insulating pattern, a contact plugpassing through the insulating pattern, a capping insulating layerdisposed on the color filter, a separation structure having a secondopening overlapping the capping insulating layer and the contact plug, afirst electrode disposed in the second opening of the separationstructure, and a photoelectric layer disposed on the first electrode.The separation structure includes a first insulating layer and a secondinsulating layer formed of different materials.

According to an aspect of the present inventive concept, an image sensoris provided. The image sensor includes a through electrode disposed in athrough hole passing through a semiconductor substrate, an insulatingpattern disposed on the semiconductor substrate and having a firstopening, a color filter disposed in the first opening of the insulatingpattern, a capping insulating layer disposed on the color filter, aseparation structure having a second opening overlapping the cappinginsulating layer, and an electrode disposed in the second opening of theseparation structure. The separation structure has an upper surfacerecessed in a direction toward the semiconductor substrate.

BRIEF DESCRIPTION OF DRAWINGS

The above, and other aspects, features, and advantages of the presentdisclosure will be more clearly understood from the following detaileddescription when taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is a block diagram of an image processing apparatus including animage sensor according to an example embodiment;

FIGS. 2A and 2B are circuit diagrams illustrating pixel circuitsincluded in an image sensor according to an example embodiment;

FIG. 3 is a plan view illustrating a semiconductor device according toan example embodiment;

FIG. 4 is a cross-sectional view illustrating an image sensor accordingto an example embodiment;

FIG. 5A is an enlarged view of region A of FIG. 4 according to anexample embodiment;

FIG. 5B is an enlarged view of region B of FIG. 4 according to anexample embodiment;

FIG. 5C is a modification of FIG. 5B;

FIG. 6A is an image sensor according to an example embodiment;

FIG. 6B is an enlarged view of region A of FIG. 6A;

FIG. 7A is an image sensor according to an example embodiment;

FIG. 7B is an enlarged view of region A of FIG. 7A;

FIG. 8 is an image sensor according to an example embodiment;

FIG. 9 is an image sensor according to an example embodiment;

FIG. 10 is an image sensor according to an example embodiment;

FIG. 11 is an image sensor according to an example embodiment;

FIG. 12 is an image sensor according to an example embodiment;

FIG. 13 is an image sensor according to an example embodiment;

FIG. 14 is an image sensor according to an example embodiment;

FIG. 15 is an image sensor according to an example embodiment;

FIG. 16 is an image sensor according to an example embodiment;

FIGS. 17A through 17H are cross-sectional views illustrating a method offorming an image sensor according to an example embodiment;

FIGS. 18A and 18B are cross-sectional views illustrating a method offorming an image sensor according to an example embodiment;

FIGS. 19A through 19F are cross-sectional views illustrating a method offorming an image sensor according to an example embodiment;

FIGS. 20A and 20B are cross-sectional views illustrating a method offorming an image sensor according to an example embodiment;

FIGS. 21A through 21E are cross-sectional views illustrating a method offorming an image sensor according to an example embodiment; and

FIGS. 22A through 22C are cross-sectional views illustrating a method offorming an image sensor according to an example embodiment.

DETAILED DESCRIPTION

An image sensor, according to an example embodiment, will be describedwith reference to FIG. 1. FIG. 1 is a block diagram of an imageprocessing apparatus 1 including an image sensor 10, according to anexample embodiment.

Referring to FIG. 1, the image processing apparatus 1 may include theimage sensor 10 and an image processor 20.

The image sensor 10 may include a pixel array 11, a row driver 12, acolumn driver 13, a timing controller 14, and a readout circuit 15.

The image sensor 10 may operate in response to a control commandreceived from the image processor 20, and may convert light reflectedfrom an external object 30 into an electrical signal and output theelectrical signal to the image processor 20. The pixel array 11 includedin the image sensor 10 may include a plurality of pixels PX. The pixelsPX may include photoelectric elements receiving light to generateelectric charges.

The row driver 12 may drive the pixel array 11 in units of rows. Forexample, the row driver 12 may generate a transfer control signalcontrolling a transfer transistor of each of the pixels PX, a resetcontrol signal controlling a reset transistor of each of the pixels PX,and a select control signal controlling a select transistor of each ofthe pixels PX.

The column driver 13 may include a correlated double sampler (CDS) andan analog-to-digital converter (ADC). The correlated double sampler(CDS) may perform correlated double sampling by receiving an electricalsignal through column lines connected to the pixels PX included in a rowselected by a row select signal supplied by the row driver 12. Theanalog-to-digital converter (ADC) may convert an output from thecorrelated double sampler (CDS) into a digital signal, and may transmitthe digital signal to the readout circuit 15.

The readout circuit 15 may include a latch or buffer circuit temporarilystoring a digital signal and an amplification circuit. The readoutcircuit 15 may temporarily store or amplify a digital signal receivedfrom the column driver 13 to generate image data.

Operation timings of the row driver 12, the column driver 13, and thereadout circuit 15 may be determined by the timing controller 14, andthe timing controller 14 may operate in response to a control commandtransmitted by the image processor 20. The image processor 20 mayperform signal processing on image data transmitted by the readoutcircuit 15, and may output the signal-processed image data to a displaydevice or the like or store the signal-processed image data in a storagedevice such as a memory.

In an example embodiment, each of the pixels PX may include two or morephotoelectric elements, and two or more photoelectric elements includedin one of the pixels PX may receive light of different colors togenerate electric charges. When the one pixel PX includes two or morephotoelectric elements, each pixel PX may include a pixel circuit toprocess electric charges generated by the two or more photoelectricelements, respectively. The pixel circuit connected to each of the twoor more photoelectric elements described above will be described withreference to FIGS. 2A and 2B. FIGS. 2A and 2B are circuit diagramsillustrating pixel circuits included in an image sensor, according to anexample embodiment.

Each of the pixels PX may include a first photoelectric element OPD ofFIG. 2A and a second photoelectric element SPD of FIG. 2B.

First, a first pixel circuit 40A of FIG. 2A, connected to the firstphotoelectric element OPD of FIG. 2A, will be described with referenceto FIG. 2A.

Referring to FIGS. 1 and 2A, the first pixel circuit 40A connected tothe first photoelectric element OPD may include a reset transistor RX, adrive transistor DX, and a select transistor SX.

A gate terminal of the drive transistor DX may be connected to afloating diffusion FD, and electric charges generated by the firstphotoelectric element OPD may be accumulated in the floating diffusionFD.

In an example embodiment, the first photoelectric element OPD mayinclude first and second electrodes disposed parallel to each other, anda photoelectric layer provided therebetween. The first and secondelectrodes may be transparent electrodes. The photoelectric layer may bean organic photoelectric layer receiving light in a predeterminedwavelength band to generate electric charges.

The drive transistor DX may operate as a source follower bufferamplifier by electric charges accumulated in the floating diffusion FD.The drive transistor DX may amplify the electrical charges accumulatedin the floating diffusion FD and transfer the amplified electricalcharges to the select transistor SX.

The select transistor SX may operate in response to a select controlsignal input by the row driver of 12 FIG. 1, and may perform switchingand addressing operations. When a select control signal from the rowdriver 12 of FIG. 1 is applied to the select transistor SX, a pixelsignal may be output to a column line connected to the select transistorSX. The output pixel signal described above may be detected by thecolumn driver 13 of FIG. 1 and the readout circuit 15 of FIG. 1.

The reset transistor RX may operate in response to a reset controlsignal input by the row driver 12 of FIG. 1. The reset control signalmay cause the reset transistor RX to reset a voltage of the floatingdiffusion FD to a readout voltage.

The first photoelectric element OPD may be an organic photoelectricconversion element or an organic photodiode. The first photoelectricelement OPD may use holes as principal charge carriers. When the holesare used as the principal charge carriers, a cathode of the firstphotoelectric element OPD may be connected to the floating diffusion FD,and an anode of the first photoelectric element OPD may be connected toan upper electrode voltage Vtop.

In an example embodiment, the upper electrode voltage Vtop may have avoltage of several volts, for example, about 3.0 V. Because holes aregenerated as principal charge carriers by the first photoelectricelement OPD, a drain terminal of the reset transistor RX may beconnected to a readout voltage having a voltage level different fromthat of a power supply voltage. The first pixel circuit 40A may beimplemented to use the holes as the principal charge carriers to improvedark current characteristics.

A second pixel circuit 40B of FIG. 2 connected to the secondphotoelectric element SPD of FIG. 2 will be described with reference toFIG. 2B.

Referring to FIGS. 1 and 2B, the second pixel circuit 40B connected tothe second photoelectric element SPD may include a reset transistor RX,a drive transistor DX, a select transistor SX, and a transfer transistorTX.

The second photoelectric element SPD may be a silicon photodiode or asilicon photoelectric conversion element formed within a semiconductorsubstrate including silicon or the like, and may be connected to afloating diffusion FD through the transfer transistor TX. A cathode oranode of the second photoelectric element SPD may not be directlyconnected to the floating diffusion FD.

The transfer transistor TX may transfer electric charges accumulated inthe second photoelectric element SPD to the floating diffusion FD, basedon a transfer control signal transmitted by the row driver 12 of FIG. 1.

The second photoelectric element SPD may generate electrons as principalcharge carriers.

Operations of the reset transistor RX, the drive transistor DX, and theselect transistor SX may be similar to those described above withreference to FIG. 2A, and a pixel signal may be output through a columnline connected to the select transistor SX. The output pixel signal maybe detected by the column driver 13 of FIG. 1 and the readout circuit 15of FIG. 1.

An example of an image sensor including the first and secondphotoelectric elements OPD and SPD will be described with reference toFIGS. 3, 4, and 5A. FIG. 3 is a plan view illustrating an image sensor,according to an example embodiment. FIG. 4 is a cross-sectional viewtaken along line I-I′ of FIG. 3, illustrating an example of an imagesensor, according to an example embodiment. FIG. 5A is an enlarged viewof region A of FIG. 4, illustrating an example of an image sensor,according to an example embodiment.

Referring to FIGS. 3, 4, and 5A, photodiodes 140 may be disposed withina semiconductor substrate 105 having a first surface 105 a and a secondsurface 105 b opposing each other. The photodiodes 140 may convert lightreceived to the photodiodes 140 into an electrical signal. Thephotodiodes 140 may be the second photoelectric element SPD describedabove with reference to FIG. 2B. The photodiodes 140 may also bereferred to using the terms “silicon photoelectric conversion element,”or “semiconductor photoelectric conversion element.”

Each of the photodiodes 140 may include a first impurity region 143 anda second impurity region 146 having different conductivity types. Thefirst impurity region 143 may be formed to be deeper than the secondimpurity region 146 from the first surface 105 a of the semiconductorsubstrate 105. The first impurity region 143 and the second impurityregion 146 may have different conductivity types. For example, one ofthe first impurity region 143 and the second impurity region 146 mayhave n-type conductivity, and the other thereof may have p-typeconductivity. For example, the second impurity region 146 may havep-type conductivity, and the first impurity region 143 may have n-typeconductivity in at least a region thereof adjacent to the secondimpurity region 146. A p-n junction between the first and secondimpurity regions 143 and 146 may be closer to the first surface 105 athan the second surface 105 b of the semiconductor substrate 105.

By an isolation region 110 within the semiconductor substrate 105,storage node regions 150 may be disposed, and the storage node regions150 may be spaced apart from the photodiodes 140. The storage noderegions 150 may have a different conductivity type from that of thesemiconductor substrate 105. For example, the semiconductor substrate105 may have p-type conductivity, and the storage node regions 150 mayhave n-type conductivity. In an example embodiment, the storage noderegions 150 may be the floating diffusion FD of FIG. 2A described abovewith reference to FIG. 2A.

A circuit interconnection region 155 may be disposed on the firstsurface 105 a of the semiconductor substrate 105. The circuitinterconnection region 155 may include a front insulating structure 180disposed on the first surface 105 a of the semiconductor substrate 105,and wiring layers 160 and front vias 165 disposed in the frontinsulating structure 180.

A support layer 185 may be disposed on the circuit interconnectionregion 155. The support layer 185 may be used to provide rigidity to thesemiconductor substrate 105. The support layer 185 may be formed of asilicon oxide, a silicon nitride, and/or a semiconductor material.

Through holes 120 may be formed through the semiconductor substrate 105.The through holes 120 may pass through between the first surface 105 aand the second surface 105 b of the semiconductor substrate 105.

In an example embodiment, the through holes 120 may pass through theisolation region 110 adjacent to the first surface 105 a of thesemiconductor substrate 105.

Through electrode structures 125 may be disposed in the through holes120.

Each of the through electrode structures 125 may include a throughelectrode 135, and an insulating spacer 130 surrounding a side surfaceof the through electrode 135.

The through electrode 135 may pass through the semiconductor substrate105, and the insulating spacer 130 may be interposed between thesemiconductor substrate 105 and the through electrode 135. The throughelectrode 135 may be formed of a conductive material, for example,polysilicon. The insulating spacer 130 may be formed of an insulatingmaterial, such as a silicon oxide and/or a silicon nitride.

An antireflective layer 205 may be disposed on the second surface 105 bof the semiconductor substrate 105.

The antireflective layer 205 may prevent the reflection of lightreceived from outside the semiconductor substrate 105 toward the secondsurface 105 b of the semiconductor substrate 105 to redirect the lightto the photodiodes 140. The antireflective layer 205 may be formed of,for example, SiON, SiC, SiCN, or SiCO.

The antireflective layer 205 may have an insulating pattern 212 disposedthereon, and the insulating pattern 212 may have first openings 212 a.The insulating pattern 212 may be formed of an insulating material, suchas a silicon oxide.

The antireflective layer 205 may have color filters 235 disposedthereon, and the color filters 235 may be spaced apart from one another.The antireflective layer 205 may be disposed between the second surface105 b of the semiconductor substrate 105 and the insulating pattern 212and between the second surface 105 b of the semiconductor substrate 105and the color filters 235.

The color filters 235 may correspond to the first openings 212 a of theinsulating pattern 212 on a one-to-one basis, and may be disposed in thefirst openings 212 a of the insulating pattern 212. The color filters235 may overlap the photodiodes 140. The color filters 235 may includefirst color filters 235 a and second color filters 235 b adjacent toeach other in row and column directions.

In an example embodiment, the first color filters 235 a may be redfilters, and the second color filters 235 b may be blue filters. Forexample, the first color filters 235 a may be red filters allowing lighthaving a red wavelength to pass therethrough to reach the photodiodes140 overlapping the first color filters 235 a, and the second colorfilters 235 b may be blue filters allowing light having a bluewavelength to pass therethrough to reach the photodiodes 140 overlappingthe second color filters 235 b.

The color filters 235 may have capping insulating layers 245 disposedthereon. In an example embodiment, the color filters 235 and the cappinginsulating layers 245 may be stacked sequentially. The color filters 235and the capping insulating layers 245 may be disposed in the firstopenings 212 a of the insulating pattern 212. Thus, each of thesequentially stacked color filters 235 and capping insulating layers 245may be surrounded by the insulating pattern 212. The capping insulatinglayers 245 may be self-aligned with the color filters 235. The cappinginsulating layers 245 may be formed of an insulating material, such as asilicon oxide. Each of the capping insulating layers 245 may have anupper surface coplanar with an upper surface of the insulating pattern212.

Insulating liners 230 may be disposed to be interposed between bottomsurfaces of the color filters 235 and the antireflective layer 205 andto extend between side surfaces of the color filters 235 and theinsulating pattern 212. The insulating liners 230 may extend between theinsulating pattern 212 and side surfaces of the capping insulatinglayers 245, while covering the side surfaces of the color filters 235.The insulating liners 230 may have upper surfaces coplanar with theupper surfaces of the capping insulating layers 245. The insulatingliners 230 may be formed of an insulating material, such as a siliconoxide.

Contact plugs 215 may be formed to continuously pass through theinsulating pattern 212 and the antireflective layer 205 and to beelectrically connected to the through electrodes 135 of the throughelectrode structures 125. The contact plugs 215 may be formed integrallyaccording to an embodiment.

Each of the contact plugs 215 may include a plug portion 217 and abarrier layer 216 covering a side surface and a bottom surface of theplug portion 217. In each contact plug 215, the plug portion 217 maycontinuously pass through the insulating pattern 212 and theantireflective layer 205, and may be formed of a metal, such astungsten. The barrier layer 216 may be formed of a conductive materialincluding a metal nitride, such as a titanium nitride.

In an example embodiment, the contact plugs 215, the insulating pattern212, the insulating liners 230, and the capping insulating layers 245may have upper surfaces coplanar with one another.

A separation structure 265 may be disposed on the insulating pattern212. The separation structure 265 may have second openings 265 a. Thesecond openings 265 a may expose the contact plugs 215 and the cappinginsulating layers 245.

In the separation structure 265, each of the second openings 265 a mayoverlap a single color filter and a single contact plug. For example,each of the second openings 265 a may expose a single capping insulatinglayer on a single color filter, and may expose a single contact plug.

The separation structure 265 may be formed of materials having etchselectivity with respect to each other, and may include first and secondinsulating layers 250 and 255 aligned in a vertical direction. One ofthe first and second insulating layers 250 and 255 may be formed of amaterial having etch selectivity with respect to the capping insulatinglayers 245. The second insulating layer 255 may be disposed on the firstinsulating layer 250. The first insulating layer 250 may be formed of amaterial having etch selectivity with respect to the capping insulatinglayers 245. The second insulating layer 255 may be thicker than thefirst insulating layer 250. The first insulating layer 250 may be formedof a material having etch selectivity with respect to the secondinsulating layer 255 and the capping insulating layers 245. The firstinsulating layer 250 may be formed of a material having etch selectivitywith respect to the second insulating layer 255, the capping insulatinglayers 245, and the insulating liners 230. For example, the secondinsulating layer 255, the capping insulating layers 245, and theinsulating liners 230 may be formed of oxide-based insulating materials,for example, a silicon oxide, and the first insulating layer 250 may beformed of a nitride-based insulating material, for example, a siliconnitride.

The first electrodes 275 may be disposed in the second openings 265 a ofthe separation structure 265. The separation structure 265 may surroundside surfaces of the first electrodes 275, as illustrated in FIG. 3.Each of the first electrodes 275 may have an upper surface coplanar withthe upper surface of the separation structure 265.

In an example embodiment, the separation structure 265 may have an uppersurface having a downwardly concave shape, as illustrated in FIG. 5A.The separation structure 265 may have an upper surface recessed in adirection toward the semiconductor substrate 105, rather than the uppersurface of each of the first electrodes 275. The separation structure265 may have an upper surface continuously extending from the uppersurfaces of the first electrodes 275 without a stepped portion andforming a curved surface. The curved surface formed by the upper surfaceof the separation structure 265 may be bent in a direction toward thesemiconductor substrate 105. The upper surface of the separationstructure 265 may have a central portion that is concave in thedirection toward the semiconductor substrate 105. For example, theseparation structure 265 may have an upper surface formed as a surfacecurved in a downward direction from the edges of the first electrodes275, while continuously extending from the upper surfaces of the firstelectrodes 275 without a stepped portion. Here, the term “downwarddirection” may refer to a direction toward the semiconductor substrate105, based on the separation structure 265.

The first electrodes 275 may fill the second openings 265 a of theseparation structure 265, and may overlap the capping insulating layers245, the color filters 235, and the contact plugs 215.

The first electrodes 275 may correspond to the color filters 235 on aone-to-one basis, and may overlap the color filters 235. For example,one of the first electrodes 275 may overlap one of the color filters235.

The first electrodes 275 may correspond to the contact plugs 215 on aone-to-one basis. The first electrodes 275 may be electrically connectedto the contact plugs 215 while being in contact with the contact plugs215. Thus, one of the first electrodes 275 may overlap one of the colorfilters 235, and may be electrically connected to one of the contactplugs 215.

The first electrodes 275 may be transparent electrodes. For example, thefirst electrodes 275 may be formed of a transparent conductive material,such as ITO, IZO, ZnO, SnO₂, an antimony-doped tin oxide (ATO), analuminium-doped zinc oxide (AZO), a gallium-doped zinc oxide (GZO),TiO₂, or a fluorine-doped tin oxide (FTO).

A photoelectric layer 280 may be disposed on the first electrodes 275and the separation structure 265. The photoelectric layer 280 may coverthe first electrodes 275 and the separation structure 265, and may beformed integrally. The photoelectric layer 280 may be in contact withthe first electrodes 275 and the upper surface of the separationstructure 265.

In an example embodiment, the photoelectric layer 280 may be an organicphotoelectric layer. For example, the photoelectric layer 280 may be anorganic photoelectric layer formed of an organic material causingphotoelectric conversion only of a particular light wavelength. Forexample, the photoelectric layer 280 may be an organic photoelectriclayer causing photoelectric conversion of a green light wavelength.

The photoelectric layer 280 may be a layer in which a p-typesemiconductor material and an n-type semiconductor material may form ap-n junction or a bulk heterojunction, may include a single layer or aplurality of layers, and may also be a layer receiving incident light,generating excitons, and then dividing the generated excitons into holesand electrons. The photoelectric layer 280 may be an organic photodiode.Each of the p-type semiconductor material and the n-type semiconductormaterial included in the photoelectric layer 280 may absorb light in agreen wavelength range, and may exhibit a significantly increasedabsorption peak in a wavelength range from about 500 nm to about 600 nm.

Each of the p-type semiconductor material and the n-type semiconductormaterial of the photoelectric layer 280 may have, for example, a bandgap of about 1.5 eV to about 3.5 eV, and may also have a band gap ofabout 2.0 eV to about 2.5 eV within the band gap range. Since having theband gap range, each of the p-type semiconductor material and the n-typesemiconductor material of the photoelectric layer 280 may absorb lightin a green wavelength range, and specifically, may exhibit asignificantly increased absorption peak in a wavelength range from about500 nm to about 600 nm.

The photoelectric layer 280 may include a single layer or a plurality oflayers. The photoelectric layer 280 may include any combination of, forexample, an intrinsic (I) layer, a p-type layer/I layer, an Ilayer/n-type layer, a p-type layer/I layer/n-type layer, and a p-typelayer/n-type layer. The I layer may include the p-type semiconductormaterial and the n-type semiconductor material mixed at a ratio of about1:100 to about 100:1. Within the mixture ratio range, the I layer mayinclude the p-type semiconductor material and the n-type semiconductormaterial mixed at a ratio of about 1:50 to about 50:1, about 1:10 toabout 10:1, or about 1:1. In the photoelectric layer 280, the p-typesemiconductor material and the n-type semiconductor material may have acomposition ratio, in the mixture ratio range, advantageous ineffectively generating excitons and a p-n junction. The p-type layer mayinclude the p-type semiconductor material, and the n-type layer mayinclude the n-type semiconductor material. The photoelectric layer 280may have a thickness of, for example, about 1 nm to about 500 nm. Thephotoelectric layer 280 may have a thickness at which the photoelectriclayer 280 may effectively increase photoelectric conversion efficiencyby effectively absorbing light and effectively dividing and transferringholes and electrons.

The photoelectric layer 280 may have a second electrode 285 disposedthereon. The second electrode 285 may be a transparent electrode. Forexample, the second electrode electrode 285 may be formed of atransparent conductive material, such as ITO, IZO, ZnO, SnO₂, ATO, AZO,GZO, TiO₂, or FTO. Thus, the first and second electrodes 275 and 285 maybe transparent electrodes.

The first and second electrodes 275 and 285 and the photoelectric layer280 therebetween may form the first photoelectric element OPD of FIG. 2Adescribed above with reference to FIG. 2A. Thus, the first and secondelectrodes 275 and 285 and the photoelectric layer 280 therebetween mayform an organic photoelectric element or an organic photoelectricconversion element.

The second electrode 285 may have a cover insulating layer 290 disposedthereon. The cover insulating layer 290 may be formed of an insulatingmaterial, such as a silicon oxide or a silicon nitride.

The cover insulating layer 290 may have microlenses 295 disposedthereon. The microlenses 295 may overlap the color filters 235. Themicrolenses 295 may redirect a path of light received to a region,except for the photodiodes 140, to concentrate the light on thephotodiodes 140.

In an example embodiment, the through holes 120 may pass through theisolation region 110. An example of the isolation region 110 and thethrough electrode structures 125 disposed in the through holes 120 willbe described with reference to FIG. 5B. FIG. 5B is an enlarged view ofregion B of FIG. 4, illustrating an example of an image sensor,according to an example embodiment. Here, one of the through holes 120and one of the through electrode structures 125 will be mainlydescribed.

Referring to FIG. 5B, the isolation region 110 may be disposed in atrench 108 formed from the first surface 105 a of the semiconductorsubstrate 105. The isolation region 110 may include a buffer oxide layer114 conformally covering an inner wall of the trench 108, a liner layer116 disposed on the buffer oxide layer, and an element separation layer118 disposed on the liner layer 116 to fill the trench 108.

Each of the through electrode structures 125 may pass through thesemiconductor substrate 105 and the isolation region 110.

One of the front vias 165 included in the circuit interconnection region155 may be in contact with the through electrode 135 of the throughelectrode structure 125. One of the front vias 165 included in thecircuit interconnection region 155 and a second conductive layer 167.The first conductive layer 166 may be interposed between the secondconductive layer 167 and the through electrode 135, and may cover a sidesurface of the second conductive layer 167.

In an example embodiment, the through electrode 135 may pass through theisolation region 110. However, example embodiments of the presentinventive concept are not limited thereto. A modification of the throughelectrode 135 will be described with reference to FIG. 5C. FIG. 5C is amodification of FIG. 5B.

Referring to FIG. 5C, the through electrode 135 may be disposed in aportion recessed from the first surface 105 a of the semiconductorsubstrate 105. The recessed portion may be filled with an insulatingmaterial 137. One of the front vias 165 included in the circuitinterconnection region 155 may pass through the insulating material 137,and may be in contact with the through electrode 135.

A modification of the separation structure 265 described above withreference to FIG. 4 will be described with reference to FIG. 6A. FIG. 6Ais a cross-sectional view taken along line I-I′ of FIG. 3, illustratingan image sensor according to an example embodiment.

Referring to FIG. 6A, a separation structure 265 may include a firstinsulating layer 250, a second insulating layer 255, and a thirdinsulating layer 260. The first and third insulating layers 250 and 260may be formed of materials having etch selectivity with respect to thesecond insulating layer 255. For example, when the second insulatinglayer 255 is formed of an oxide-based insulating material, for example,a silicon oxide, the first and third insulating layers 250 and 260 maybe formed of nitride-based insulating materials, for example, a siliconnitride. When the second insulating layer 255 is formed of anitride-based insulating material, for example, a silicon nitride, thefirst and third insulating layers 250 and 260 may be formed ofoxide-based insulating materials, for example, a silicon oxide.

An example of an image sensor, according to an example embodiment, willbe described with reference to FIG. 6B. FIG. 6B is an enlarged view ofregion A, illustrating the example of the image sensor, according to anexample embodiment.

Referring to FIG. 6B, at least a portion of the separation structure265, adjacent to the upper surface of the separation structure 265, maybe formed of a material harder than a first electrode 275. Theseparation structure 265 may have an upper surface continuouslyextending from an upper surface of the first electrode 275 without astepped portion and forming a curved surface. For example, in astructure of the separation structure 265 described above with referenceto 6A, the third insulating layer 260 may be formed of a material harderthan the first electrode 275, for example, a nitride-based insulatingmaterial, and an upper surface of the third insulating layer 260 may beconvex in an upward direction. Here, the term “upward direction” mayrefer to a direction in which the upper surface of the third insulatinglayer 260 is removed from the semiconductor substrate 105. Theseparation structure 265 may have an upper surface which is convex inthe upward direction as being removed from the first electrode 275,while continuously extending from the upper surface of the firstelectrode 275. When the third insulating layer 260 is formed of amaterial softer than the first electrode 275, for example, a siliconoxide, the upper surface of the separation structure 265 may form asurface curved in a downward direction, similarly to the upper surfaceof the separation structure 265 described above with reference to 5A.

A modification of the separation structure 265 described above withreference to FIG. 4 and components adjacent to the separation structure265 will be described with reference to FIGS. 7A and 7B. FIG. 7A is across-sectional view taken along line I-I′ of FIG. 3, illustrating animage sensor according to an example embodiment. FIG. 7B is an enlargedview of region A of FIG. 7A.

Referring to FIGS. 7A and 7B, a separation structure 265 may includesequentially stacked first and second insulating layers 250 and 255, anda base insulating layer 220 disposed below the first insulating layer250. The base insulating layer 220 may be formed of a material havingetch selectivity with respect to the insulating liners 230 and thecapping insulating layers 245. For example, the base insulating layer220 may be formed of a nitride-based insulating material, for example, asilicon nitride, and the insulating liners 230 and the cappinginsulating layers 245 may be formed of oxide-based insulating materials,for example, a silicon oxide.

The base insulating layer 220 may have a width less than that of thefirst insulating layer 250. The first and second insulating layers 250and 255 may have the same width as each other, and may be aligned in avertical direction. One of opposing side surfaces of the base insulatinglayer 220 may be aligned with one side surface of the first insulatinglayer 250 in a vertical direction, and the other of the opposing sidesurfaces of the base insulating layer 220 may be in contact with a lowersurface of the first insulating layer 250.

The separation structure 265 may have a first lower surface 220 a and asecond lower surface 250 a positioned on different levels. The firstlower surface 220 a of the separation structure 265 may be closer to asecond surface 105 b of a semiconductor substrate 105 than the secondlower surface 250 a of the separation structure 265. The first lowersurface 220 a of the separation structure 265 may be closer to contactplugs 215 than the second lower surface 250 a of the separationstructure 265.

The first lower surface 220 a of the separation structure 265 may be alower surface of the base insulating layer 220, and the second lowersurface 250 a of the separation structure 265 may be a lower surface ofthe first insulating layer 250 not being in contact with the baseinsulating layer 220.

The insulating pattern 212 and the contact plugs 215 may have uppersurfaces coplanar with each other.

The capping insulating layers 245 and the insulating liners 230 may haveupper surfaces coplanar with each other.

The upper surfaces of the insulating pattern 212 and the contact plugs215 may be closer to the second surface 105 b of the semiconductorsubstrate 105 than the upper surfaces of the capping insulating layers245.

Each of first electrodes 275 disposed in second openings 265 a of theseparation structure 265 may have a first lower surface 275 a and asecond lower surface 275 b positioned on different levels. In each firstelectrode 275, the first lower surface 275 a may be closer to the secondsurface 105 b of the semiconductor substrate 105 than the second lowersurface 275 b.

The first lower surfaces 220 a of the first electrodes 275 may be incontact with the contact plugs 215 and the insulating pattern 212, andthe second lower surfaces 275 b of the first electrodes 275 may be incontact with the capping insulating layers 245.

The separation structure 265 may have an upper surface continuouslyextending from the upper surfaces of the first electrodes 275 without astepped portion and forming a curved surface, curved in a downwarddirection.

As described above, the separation structure 265 may have the uppersurface formed as the curved surface. Similarly, separation structuresto be described with reference to the following example embodiments mayalso have upper surfaces formed as curved surfaces. Although notspecifically described below, the separation structures to be describedbelow may be understood as having upper surfaces formed as curvedsurfaces.

A modification of the separation structure 265 described above withreference to FIGS. 7A and 7B will be described with reference to FIG. 8.FIG. 8 is a cross-sectional view taken along line I-I′ of FIG. 3,illustrating an image sensor according to an example embodiment.

Referring to FIG. 8, a separation structure 265 may further include athird insulating layer 260 disposed on a second insulating layer 255, inaddition to the base insulating layer 220, the first insulating layer250, and the second insulating layer 255, described above with referenceto FIGS. 7A and 7B. The third insulating layer 260 may be formed of amaterial having etch selectivity with respect to the second insulatinglayer 255.

A modification of the capping insulating layers 245, the insulatingliners 230, and the first electrodes 275, described above with referenceto FIGS. 7A and 7B, will be described with reference to FIG. 9. FIG. 9is a cross-sectional view taken along line I-I′ of FIG. 3, illustratingan image sensor according to an example embodiment.

Referring to FIG. 9, each of capping insulating layers 245 may have anupper surface coplanar with the upper surfaces of the insulating pattern212 and the contact plugs 215. Each of insulating liners 230 may includea portion in contact with a lower surface of the separation structure265, and a portion having an upper surface coplanar with the uppersurface of the capping insulating layer 245. First electrodes 275 may bedisposed in the second openings 265 a of the separation structure 265,and may each have a substantially flat lower surface.

As described above, the capping insulating layers 245 and the colorfilters 235 may be in contact with each other. However, exampleembodiments of the present inventive concept are not limited thereto.For example, one of the examples of the image sensor described abovewith reference to FIGS. 4 through 9 may be modified, such that thecapping insulating layers 245 may be spaced apart from the color filters235. Various examples of the capping insulating layers 245 and the colorfilters 235 spaced apart from each other will be described withreference to FIGS. 10 through 14. FIG. 10 is a cross-sectional viewtaken along line I-I′ of FIG. 3, illustrating a modification of theimage sensor described above with reference to FIG. 4. FIG. 11 is across-sectional view taken along line I-I′ of FIG. 3, illustrating amodification of the image sensor described above with reference to FIG.6A. FIG. 12 is a cross-sectional view taken along line I-I′ of FIG. 3,illustrating a modification of the image sensor described above withreference to FIG. 7A. FIG. 13 is a cross-sectional view taken along lineI-I′ of FIG. 3, illustrating a modification of the image sensordescribed above with reference to FIG. 9.

Referring to FIGS. 10 through 13, filter protection layers 240 may bedisposed to be interposed between the capping insulating layers 245 andthe color filters 235 and to extend onto side surfaces of the cappinginsulating layers 245. The filter protection layers 240 may beinterposed between the capping insulating layers 245 and the insulatingliners 230. Thus, the capping insulating layers 245 may be spaced apartfrom the color filters 235 by the filter protection layers 240. Thefilter protection layers 240 may have a material having etch selectivitywith respect to the capping insulating layers 245. For example, thefilter protection layers 240 may be formed of a silicon nitride, and thecapping insulating layers 245 may be formed of a silicon oxide.

A modification of the filter protection layers 240 described above withreference to FIGS. 10 through 13 will be described with reference toFIG. 14. FIG. 14 is a cross-sectional view illustrating a modificationof the image sensor of FIG. 10, illustrating the modification of thefilter protection layers 240 described above with reference to FIGS. 10through 13.

Referring to FIG. 14, filter protection layers 240 may extend in ahorizontal direction, while being interposed between capping insulatinglayers 245 and color filters 235, may extend into insulating liners 230,and may extend in a vertical direction to cover side surfaces of thecapping insulating layers 245.

Other modifications of an image sensor, according to an exampleembodiment, will be described with reference to FIGS. 15 and 16. FIG. 15is a cross-sectional view taken along line I-I′ of FIG. 3, illustratinganother modification of the image sensor, according to an exampleembodiment. FIG. 16 is a cross-sectional view taken along line I-I′ ofFIG. 3, illustrating another modification of the image sensor, accordingto an example embodiment.

Referring to FIG. 15, a semiconductor substrate 105, photodiodes 140,through electrode structures 125, a circuit interconnection region 155,a support layer 185, an antireflective layer 205, an insulating pattern212, and contact plugs 215, equal to those described above withreference to FIG. 4, may be provided.

Each of contact protection layers 1220 may be disposed on the insulatingpattern 212, and may be aligned with the insulating pattern 212 in avertical direction. The contact protection layer 1220 may prevent thecontact plugs 215 from being damaged by an image sensor formationprocess. The contact protection layer 1220 may be formed of aninsulating material having etch selectivity with respect to theinsulating pattern 212. For example, the contact protection layer 1220may be formed of a silicon nitride, and the insulating pattern 212 maybe formed of a silicon oxide.

Color filters 235 may be disposed on the antireflective layer 205. Thecolor filters 235 may be disposed in first openings 212 a of theinsulating pattern 212. The color filters 235 may include first colorfilters 235 a, for example, red filters, and second color filters 235 b,for example, blue filters.

In an example embodiment, each of the color filters 235 may have anupper surface having a downwardly concave shape. For example, each colorfilter 235 may have an upper surface recessed in a downward directionfrom the edges of the contact protection layer 1220, while continuouslyextending from an upper surface of the contact protection layer 1220.

A capping insulating layer 1005 may be disposed on the contactprotection layer 1220 and the color filter 235. The capping insulatinglayer 1005 may extend onto the upper surface of the contact protectionlayer 1220, while covering the upper surface of the color filter 235.The capping insulating layer 1005 may be formed of a silicon oxide. Thecapping insulating layer 1005 may have a flat upper surface.

Each of holes 1006 may be formed through the capping insulating layer1005 and the contact protection layer 1220, and may expose each of thecontact plugs 215. Conductive vias 1010 may be disposed in the holes1006. The conductive vias 1010 may also be referred to as a “rear via”or an “electrode via.”

In an example embodiment, the conductive vias 1010 may be formed of ametal nitride, such as TiN or TaN. Alternatively, the conductive vias1010 may also be formed of a transparent electrode material.

The capping insulating layer 1005 may have a separation structure 265and first electrodes 275 disposed thereon and having the same structuresas those described above with reference to FIG. 4. The separationstructure 265 may include a first insulating layer 250 and a secondinsulating layer 255 equal to those described above with reference toFIG. 4, and the first and second insulating layers 250 and 255 may bestacked sequentially, and may have etch selectivity with respect to eachother. The first electrodes 275 may be disposed in second openings 265 aof the separation structure 265, may be electrically connected to theconductive vias 1010, while being in contact with the conductive vias1010, and may overlap the color filters 235. The first electrodes 275may form interfaces IN with the conductive vias 1010.

The conductive vias 1010 may be disposed between the first electrodes275 and the contact plugs 215, while passing through the cappinginsulating layers 1005 and the contact protection layers 1220. The firstelectrodes 275 and the contact plugs 215 may be in contact with theconductive vias 1010. The first electrodes 275 and the contact plugs 215may be electrically connected through the conductive vias 1010.

The photoelectric layer 280, the second electrode 285, the coverinsulating layer 290, and the microlenses 295, described above withreference to FIG. 4, may be disposed on the separation structure 265 andthe first electrodes 275.

The conductive vias 1010 may be formed using a process different fromthat of forming the first electrodes 275, and may form the interfaces INwith the first electrodes 275. However, example embodiments of thepresent inventive concept are not limited thereto. For example, in amodification, as illustrated in FIG. 16, first electrodes 1275 eachincluding a conductive via portion 1275 a corresponding to each of theconductive vias 1010 of FIG. 15 and an electrode portion 1275 bcorresponding to each of the first electrodes 275 of FIG. 15 may also beprovided. In each first electrode 1275 of FIG. 16, the conductive viaportion 1275 a and the electrode portion 1275 b may be formedintegrally. The conductive via portion 1275 a of the first electrode1275 may also be referred to as a “conductive via,” and the electrodeportion 1275 b of the first electrode 1275 may also be referred to as a“transparent electrode.”

An upper surface of the separation structure 265 may be formed as asurface curved in a direction toward the semiconductor substrate 105,while continuously extending from the upper surfaces of the firstelectrodes 275 without a stepped portion, as illustrated in FIG. 5A.

The following will describe methods of forming various examples of theimage sensor according to an example embodiment described above, withreference to FIGS. 17A through 17H, 18A, 18B, 19A through 19F, 20A, 20B,21A through 21E, and 22A through 22C. FIGS. 17A through 17H, 18A, 18B,19A through 19F, 20A, 20B, 21A through 21E, and 22A through 22C arecross-sectional views taken along line I-I′ of FIG. 3, illustrating themethods of forming various examples of the image sensor according to anexample embodiment.

First, an example of a method of forming a structure of the image sensordescribed above with reference to FIGS. 3 and 4 will be described withreference to FIGS. 17A through 17H.

Referring to FIGS. 3 and 17A, an isolation region 110 may be formed on afirst surface 105 a of a semiconductor substrate 105. The isolationregion 110 may be a trench isolation region.

Through holes 120 may be formed through a portion of the isolationregion 110, and may extend into the semiconductor substrate 105. Throughelectrode structures 125 may be formed in the through holes 120. Theforming of the through electrode structures 125 may include forminginsulating spacers 130 on inner walls of the through holes 120 andforming through electrodes 135 filling the through holes 120. Thethrough electrodes 135 may be formed of polysilicon.

An ion implantation process may be performed on the first surface 105 aof the semiconductor substrate 105 to form storage node regions 150 andphotodiodes 140. In an example embodiment, the storage node regions 150may have n-type conductivity. Each of the photodiodes 140 may include afirst impurity region 143 and a second impurity region 146 havingdifferent conductivity types. For example, one of the first impurityregion 143 and the second impurity region 146 may have n-typeconductivity, and the other of the first impurity region 143 and thesecond impurity region 146 may have n-type conductivity may have p-typeconductivity.

A circuit interconnection region 155 may be disposed on the firstsurface 105 a of the semiconductor substrate 105. The circuitinterconnection region 155 may include wiring layers 160 and front vias165 forming a gate and wirings of a pixel circuit, and a frontinsulating structure 180 covering the wiring layers 160 and the frontvias 165. A support layer 185 may be disposed on the circuitinterconnection region 155.

Subsequent to forming the support layer 185, a grinding process or aback-grinding process for reducing a thickness of the semiconductorsubstrate 105 may be performed to expose the through electrodes 135 ofthe through electrode structures 125. As the thickness of thesemiconductor substrate 105 decreases, an exposed surface of each of thethrough electrode structures 125 may be defined as a second surface 105b. The second surface 105 b of the semiconductor substrate 105 mayoppose the first surface 105 a on which the circuit interconnectionregion 155 is formed.

Referring to FIGS. 3 and 17B, an antireflective layer 205 may be formedon the second surface 105 b of the semiconductor substrate 105. Aninsulating layer 210 may be formed on the antireflective layer 205 tohave a thickness greater than that of the antireflective layer 205.

Contact plugs 215 may be formed to pass sequentially through theinsulating layer 210 and the antireflective layer 205, and may be incontact with the through electrodes 135. Each of the contact plugs 215may include a plug portion 217 and a barrier layer 216 covering a sidesurface and a bottom surface of the plug portion 217.

Referring to FIGS. 3 and 17C, the insulating layer 210 of FIG. 17B maybe patterned to form an insulating pattern 212 having first openings 212a. Each of the first openings 212 a may overlap the photodiodes 140. Thecontact plugs 215 may remain, to pass through the insulating pattern212. The first openings 212 a of the insulating pattern 212 may exposethe antireflective layer 205.

Referring to FIGS. 3 and 17D, an insulating liner 230 may be formed toconformally cover the insulating pattern 212 and the antireflectivelayer 205. The insulating liner 230 may be formed of a silicon oxide.Color filters 235 may be formed on the insulating liner 230 to fillportions of the first openings 212 a.

Referring to FIGS. 3 and 17E, capping insulating layers 245 may beformed on the color filters 235. The forming of the capping insulatinglayers 245 may include forming a capping layer on the second surface 105b of the semiconductor substrate 105 having the color filters 235, andplanarizing the capping layer until the through electrode structures 125are exposed. The insulating liner 230 may remain in the first openings212 a of the insulating pattern 212, while planarizing the cappinglayer, and may be formed as a plurality of insulating liners 230 spacedapart from one another.

Referring to FIGS. 3 and 17F, a first insulating layer 250 and a secondinsulating layer 255 may be formed on the capping insulating layers 245and the insulating pattern 212 to be stacked sequentially thereon.

The first insulating layer 250 may be formed of a material having etchselectivity with respect to the second insulating layer 255, the cappinginsulating layers 245, the insulating pattern 212, and the insulatingliners 230. For example, the first insulating layer 250 may be formed ofa silicon nitride, and the second insulating layer 255, the cappinginsulating layers 245, the insulating pattern 212, and the insulatingliners 230 may be formed of silicon oxides.

Referring to FIGS. 3 and 17G, the first and second insulating layers 250and 255 may be patterned to form a separation structure 265 havingsecond openings 265 a. The second openings 265 a of the separationstructure 265 may expose the contact plugs 215, and may overlap thecolor filters 235. The separation structure 265 may be formed of theremaining first insulating layer 250 and the remaining second insulatinglayer 255. In an example embodiment, the separation structure 265 may bein contact with the insulating pattern 212 and the insulating liners230.

The forming of the separation structure 265 having the second openings265 a by patterning the first and second insulating layers 250 and 255may include exposing the first insulating layer 250 by patterning thesecond insulating layer 255, and etching the exposed first insulatinglayer 250.

Since the first insulating layer 250 may be formed of a material havingetch selectivity with respect to the second insulating layer 255, thecapping insulating layers 245, the insulating pattern 212, and theinsulating liners 230, the first insulating layer 250 may be etchedselectively. Thus, the capping insulating layers 245 may be preventedfrom being damaged by etching, while forming the separation structure265. As a result, a reduction or deterioration in resolution of theimage sensor that may occur due to etching damage to the cappinginsulating layers 245 protecting the color filters 235 may be prevented.

Referring to FIGS. 3 and 17H, first electrodes 275 may be formed in thesecond openings 265 a of the separation structure 265. The forming ofthe first electrodes 275 may include forming a transparent electrodematerial layer on the semiconductor substrate 105 having the separationstructure 265, and planarizing the transparent electrode material layeruntil an upper surface of the separation structure 265 is exposed. Theplanarization process may be a chemical mechanical polishing (CMP)process.

Referring again to FIGS. 3 and 4, a photoelectric layer 280, a secondelectrode 285, and a cover insulating layer 290 may be formed on thefirst electrodes 275 and the separation structure 265 to be stackedsequentially thereon. Microlenses 295 may be formed on the coverinsulating layer 290. Thus, the image sensor described above withreference to FIGS. 3 and 4 may be fabricated.

An example of a method of forming a structure of the image sensordescribed above with reference to FIG. 6A will be described withreference to FIGS. 18A and 18B.

Referring to FIGS. 3 and 18A, the same semiconductor substrate 105 asthat described above with reference to FIGS. 17A through 17E may beprovided. For example, the same semiconductor substrate 105 as thatdescribed above with reference to FIG. 17E may be provided, and may havethe insulating pattern 212 and the contact plugs 215 exposed and thecapping insulating layers 245 formed thereon.

A first insulating layer 250, a second insulating layer 255, and a thirdinsulating layer 260 may be formed on the capping insulating layers 245and the insulating pattern 212 to be stacked sequentially thereon. Thefirst and second insulating layers 250 and 255 may be the same as thosedescribed above with reference to FIG. 17F. The third insulating layer260 may be formed of a material having etch selectivity with respect tothe second insulating layer 255, for example, a silicon nitride.

Referring to FIGS. 3 and 18B, the first to third insulating layers 250,255, and 260 may be patterned to form a separation structure 265 havingsecond openings 265 a. The forming of the separation structure 265having the second openings 265 a by patterning the first to thirdinsulating layers 250, 255, and 260 may include exposing the firstinsulating layer 250 by patterning the second and third insulatinglayers 255 and 260, and selectively etching the exposed first insulatinglayer 250. Thus, as described above with reference to FIG. 17G, sincethe capping insulating layers 245 may be prevented from being damaged byetching while forming the separation structure 265, a reduction ordeterioration in resolution of the image sensor that may occur due toetching damage to the capping insulating layers 245 may be avoided.

A transparent electrode material layer may be formed on thesemiconductor substrate 105 having the separation structure 265, and maybe planarized until the separation structure 265 is exposed to formfirst electrodes 275 defined in the second openings 265 a of theseparation structure 265.

The planarizing of the transparent electrode material layer may includeperforming a planarization process using the third insulating layer 260of the separation structure 265 as a planarization stop layer. Theplanarization process may be a CMP process. Using the third insulatinglayer 260 as a planarization stop layer may prevent a thickness of thesecond insulating layer 255 from being reduced. Thus, the firstelectrodes 275 may have a uniform thickness. As a result, distributioncharacteristics of the image sensor may be increased.

An example of a method of forming a structure of the image sensordescribed above with reference to FIG. 7A will be described withreference to FIGS. 19A through 19F.

Referring to FIGS. 3 and 19A, the same semiconductor substrate 105 asthat described above with reference to FIGS. 17A and 17B may beprovided. For example, a base insulating layer 220 may be formed on thesame semiconductor substrate 105 as that described above with referenceto FIG. 17B, and the semiconductor substrate 105 may have the insulatingpattern 212 and the contact plugs 215 exposed and the capping insulatinglayers 245 formed thereon.

Referring to FIGS. 3 and 19B, the insulating layer 210 and the baseinsulating layer 220 may be patterned. Thus, the insulating layer 210may be patterned to be formed as an insulating pattern 212 having firstopenings 212 a, and the base insulating layer 220 may remain on theinsulating pattern 212. The base insulating layer 220 remaining on theinsulating pattern 212 may cover the contact plugs 215.

Referring to FIGS. 3 and 19C, an insulating liner 230 may be conformallyformed on the second surface 105 b of the semiconductor substrate 105having the insulating pattern 212 and the base insulating layer 220,color filters 235 may be formed on the insulating liner 230 to fillportions of the first openings 212 a of the insulating pattern 212, acapping insulating layer 245 may be formed to cover the color filters235 and the insulating liner 230, and a planarization process using thebase insulating layer 220 as a planarization stop layer may be performedto planarize the capping insulating layer 245 and the insulating liner230. The planarization process may be a CMP process. The cappinginsulating layer 245 may be planarized to be formed as a plurality ofcapping insulating layers 245 spaced apart from one another, and theinsulating liner 230 may be planarized to be formed as a plurality ofinsulating liners 230 spaced apart from one another. The cappinginsulating layers 245 and the insulating liners 230 may have uppersurfaces coplanar with the base insulating layer 220.

Using the base insulating layer 220 as a planarization stop layer maysignificantly reduce a dishing effect of the capping insulating layers245 that may occur during the planarization process. Since theplanarization process may prevent the upper surfaces of the cappinginsulating layers 245 from being recessed, the capping insulating layers245 may stably protect the color filters 235. Thus, a deterioration inperformance or productivity of the image sensor, due to damage to ordeformation of the capping insulating layers 245 that may occur by theplanarization process, may be prevented.

Referring to FIGS. 3 and 19D, a first insulating layer 250 and a secondinsulating layer 255 may be formed sequentially to cover the baseinsulating layer 220, the insulating liners 230, and the cappinginsulating layers 245. The base insulating layer 220 and the firstinsulating layer 250 may be formed of the same material. The baseinsulating layer 220 and the first insulating layer 250 may also beformed of materials having etch selectivity with respect to the secondinsulating layer 255 and the capping insulating layers 245.

Referring to FIGS. 3 and 19E, the second insulating layer 255 may bepatterned to expose the first insulating layer 250, and the firstinsulating layer 250 and the base insulating layer 220 may be etchedselectively to form a separation structure 265 having second openings265 a exposing the capping insulating layers 245 and the contact plugs215. Thus, as described above with reference to FIG. 17G, since thecapping insulating layers 245 may be prevented from being damaged byetching while forming the separation structure 265, a reduction ordeterioration in resolution of the image sensor that may occur due toetching damage to the capping insulating layers 245 may be avoided.

Referring to FIGS. 3 and 19F, first electrodes 275 may be formed to fillthe second openings 265 a.

In another example embodiment, a third insulating layer 260 may befurther formed on the second insulating layer 255 described above withreference to FIG. 19D, in order to form the same separation structure265 as that described above with reference to FIG. 8. The thirdinsulating layer 260 as described above with reference to FIG. 18B maycause the first electrodes 275 to have a uniform thickness. Thus,distribution characteristics of the image sensor may be increased.

In another example embodiment, in order to form the same firstelectrodes 275 as those described above with reference to FIG. 9, thefirst insulating layer 250 and the base insulating layer 220 may beformed and then portions of the capping insulating layers 245 and theinsulating liners 230 may be etched, or portions of the cappinginsulating layers 245 and the insulating liners 230 may be etchedsimultaneously while etching the first insulating layer 250 and the baseinsulating layer 220, as described above with reference to FIG. 19E.

An example of a method of forming a structure of the image sensordescribed above with reference to FIG. 10 will be described withreference to FIGS. 20A and 20B.

Referring to FIGS. 3 and 20A, the same semiconductor substrate 105 asthat described above with reference to FIGS. 17A through 17D may beprovided, and may have the color filters 235 formed thereon. A filterprotection layer 240 may be conformally formed on the semiconductorsubstrate 105 having the color filters 235 formed thereon. The filterprotection layer 240 may protect the color filters 235.

Referring to FIGS. 3 and 20B, a capping insulating layer 245 may beformed on the filter protection layer 240, and the filter protectionlayer 240 and the capping insulating layer 245 may be planarized. Thus,an image sensor including the same filter protection layer 240 as thatdescribed above with reference to FIG. 11 may be fabricated.

In another example embodiment, in order to form the same filterprotection layer 240 as that described above with reference to FIG. 14,a process of etching a portion of the insulating liner 230 and formingthe filter protection layer 240 may be performed prior to forming thefilter protection layer 240 of FIG. 20A.

An example of a method of forming a structure of the image sensordescribed above with reference to FIG. 15 will be described withreference to FIG. 21A through 21E.

Referring to FIGS. 3 and 21A, the same semiconductor substrate 105 asthat described above with reference to FIGS. 19A and 19B may beprovided, and may have the insulating pattern 212 having the firstopenings 212 a, and the base insulating layer 220 of FIG. 19B formed onthe insulating pattern 212. Here, the base insulating layer 220 of FIG.19B may be referred to as a contact protection layer 1220 of FIG. 21A.Thus, the base insulating layer 220 of FIG. 19B described above withreference to FIG. 19B and the contact protection layer 1220 of FIG. 21Adescribed above with reference to FIG. 21A may be understood as the samecomponent formed of the same material and to have the same thickness.

The first openings 212 a of the insulating pattern 212 may be filledwith color filters 235. The contact protection layer 1220 may preventthe contact plugs 215 from being corroded by a process of forming thecolor filters 235 by covering the contact plugs 215 formed in theinsulating pattern 212.

Referring to FIGS. 3 and 21B, an insulating material may be formed onthe contact protection layer 1220 and the color filters 235, and theinsulating material may be planarized to form a capping insulating layer1005 having a flat upper surface. The capping insulating layer 1005 maybe formed of a silicon oxide.

Holes 1006 may be formed through the capping insulating layer 1005 andthe contact protection layer 1220, and may expose the contact plugs 215.

Referring to FIGS. 3 and 21C, conductive vias 1010 may be formed to fillthe holes 1006. In an example embodiment, the conductive vias 1010 maybe formed of a metal nitride, such as TiN or TaN. Alternatively, theconductive vias 1010 may also be formed of a transparent electrodematerial.

First and second insulating layers 250 and 255 may be formedsequentially on the capping insulating layer 245 to cover the conductivevias 1010 and to have etch selectivity with respect to each other. Thefirst insulating layer 250 may have a thickness less than that of thesecond insulating layer 255. The first insulating layer 250 may beformed of a material having high etch selectivity with respect to thecapping insulating layer 1005. For example, the first insulating layer250 may be formed of a silicon nitride, and the second insulating layer255 and the capping insulating layer 1005 may be formed of siliconoxides.

Referring to FIGS. 3 and 21D, the first and second insulating layers 250and 255 may be patterned to form a separation structure 265 havingsecond openings 265 a. Each of the second openings 265 a may expose oneof the conductive vias 1010 and may overlap one of the color filters235.

The forming of the separation structure 265 may include exposing thefirst insulating layer 250 by patterning the second insulating layer255, and forming the second openings 265 a while significantly reducingetching damage to the capping insulating layer 1005 by selectivelyetching the first insulating layer 250 formed to have a thickness lessthan that of the second insulating layer 255 while having high etchselectivity with respect to the capping insulating layer 1005.

Referring to FIGS. 3 and 21E, the same process as that described abovewith reference to FIG. 17H may be performed to form first electrodes 275filling the second openings 265 a. Subsequently, a photoelectric layer280, a second electrode 285, and a cover insulating layer 290 may beformed on the first electrodes 275 and the separation structure 265 tobe stacked sequentially thereon. Microlenses 295 may be formed on thecover insulating layer 290. Thus, the image sensor described above withreference to FIG. 15 may be fabricated.

An example of a method of forming a structure of the image sensordescribed above with reference to FIG. 16 will be described withreference to FIGS. 22A through 22C.

Referring to FIGS. 3 and 22A, the same semiconductor substrate 105 asthat described above with reference to FIG. 21A may be provided, and mayhave the color filters 235 formed thereon. A capping insulating layer1005, a first insulating layer 250, and a second insulating layer 255may be formed sequentially to cover the color filters 235 and thecontact protection layer 1220. The capping insulating layer 1005, thefirst insulating layer 250, and the second insulating layer 255 may beformed of the same material and to have the same thickness as thosedescribed above with reference to FIGS. 21B and 21C.

Referring to FIGS. 3 and 22B, the first and second insulating layers 250and 255 may be patterned to form the same separation structure 265 asthat described above with reference to FIG. 21D. The separationstructure 265 may have second openings 265 a overlapping the contactplugs 215 and the color filters 235.

A mask 1015 may be formed on the capping insulating layer 1005 to coverthe separation structure 265. The mask 1015 may have an opening exposinga portion of the capping insulating layer 1005. An etching process usingthe mask 1015 as an etching mask may be performed to form holes 1006passing through the capping insulating layer 1005 and the contactprotection layer 1220 and exposing the contact plugs 215.

Referring to FIGS. 3 and 22C, the mask 1015 of FIG. 22B may beselectively removed. Subsequently, a transparent electrode material maybe formed on the second surface 105 b of the semiconductor substrate 105having the holes 1006 and the second openings 265 a, and the transparentelectrode material may be planarized until an upper surface of theseparation structure 265 is exposed to form first electrodes 1275filling the holes 1006 and the second openings 265 a. The planarizationprocess may be a CMP process. The first electrodes 1275 may includeconductive via portions 1275 a formed in the holes 1006, and electrodeportions 1275 b formed in the second openings 265 a.

The methods of forming various examples of the image sensor, accordingto an example embodiment, may be performed using the planarizationprocess and the etching process. Example embodiments may provide themethod of forming the image sensor and/or the structure of the imagesensor, which may prevent the capping insulating layers 245 or 1005protecting the color filters 235 from being damaged by the planarizationprocess and/or the etching process during the planarization processand/or the etching process. For example, as previously described, theimage sensor, according to example embodiments, may include the firstelectrodes 275 and 1275 respectively formed on the capping insulatinglayers 245 and 1005, and the separation structure 265 surrounding thefirst electrodes 275 or 1275. The separation structure 265 may includeat least two first and second insulating layers 250 and 255 havingdifferent etch selectivity, and the first insulating layer 250 disposedbelow the second insulating layer 255 may be formed of a material havingetch selectivity with respect to the capping insulating layers 245 or1005. The structure of the separation structure 265 including the firstand second insulating layers 250 and 255 described above may prevent thecapping insulating layers 245 and 1005 from being damaged during theprocess of forming the first electrodes 275 and 1275, respectively, asmentioned above in detail.

Thus, a reduction or deterioration in the resolution of the image sensorthat may occur due to damage to the capping insulating layers 245 or1005 protecting the color filters 235 may be prevented. As a result,defects may be reduced, thereby increasing productivity of the imagesensor. Further, the image sensor may have high resolution.

Further, according to example embodiments, the first electrodes 275 or1275 may be formed to have a substantially uniform thickness. Thus,distribution characteristics of the image sensor may be increased. As aresult, according to example embodiments, the image sensor including astable and reliable color filter and electrode may be provided.

As set forth above, according to example embodiments of the presentinventive concept, an image sensor including a stable and reliable colorfilter and electrode may be provided. Further, the image sensor may beminiaturized by forming a photoelectric layer that may causephotoelectric change at a wavelength of green light on a red and/or bluefilter layer.

While exemplary embodiments have been shown and described above, it willbe apparent to those skilled in the art that modifications andvariations could be made without departing from the scope of the presentinventive concept, as defined by the appended claims.

What is claimed is:
 1. An image sensor, comprising: a semiconductorsubstrate having a first surface and a second surface opposing the firstsurface; a circuit interconnection region under the first surface of thesemiconductor substrate; color filters on the second surface of thesemiconductor substrate; an insulating pattern on the second surface ofthe semiconductor substrate, wherein at least a portion of theinsulation pattern is between the color filters; through holes passingthrough the semiconductor substrate; through electrodes in the throughholes; contact plugs passing through the insulating pattern andcontacting the through electrodes; first electrodes contacting thecontact plugs and overlapping the color filters; separation structurebetween the first electrodes; and a photoelectric layer on the firstelectrodes and the separation structure, wherein the separationstructure includes a first insulating layer and a second insulatinglayer on the first insulating layer, wherein a side surface of the firstinsulating layer is aligned with a side surface of the second insulatinglayer.
 2. The image sensor of claim 1, wherein a thickness of the secondinsulating layer is greater than a thickness of the first insulatinglayer.
 3. The image sensor of claim 1, wherein an entire upper surfaceof the first insulating layer contacts an entire lower surface of thesecond insulating layer.
 4. The image sensor of claim 1, wherein amaterial of the first insulating layer is different from a material ofthe second insulating layer.
 5. The image sensor of claim 1, wherein anentire side surface of any one of the first electrodes contacts a sidesurface of the separation structure.
 6. The image sensor of claim 1,wherein a width of an upper surface of any one of the through electrodesis greater than a width of a lower surface of any one of the contactplugs.
 7. The image sensor of claim 1, further comprising: anantireflective layer between the insulating pattern and the secondsurface of the semiconductor substrate, and between the color filtersand the second surface of the semiconductor substrate.
 8. The imagesensor of claim 7, further comprising: an insulating liner interposedbetween the antireflective layer and the color filters and extendingbetween the insulating pattern and the color filters, wherein theinsulating liner is formed of a material different from a material ofthe first insulating layer.
 9. The image sensor of claim 1, furthercomprising: a photodiode in the semiconductor substrate; and a secondelectrode on the photoelectric layer, wherein the photoelectric layerand the second electrode overlap the first electrodes and the separationstructure, wherein the first electrodes and the second electrode aretransparent electrodes, and wherein the photoelectric layer is anorganic photoelectric layer.
 10. The image sensor of claim 1, furthercomprising capping insulating layers on upper surfaces of the colorfilters, wherein the capping insulating layers have upper surfacescoplanar with an upper surface of the insulating pattern.
 11. An imagesensor, comprising: a semiconductor substrate having a first surface anda second surface opposing the first surface; a circuit interconnectionregion under the first surface of the semiconductor substrate; anantireflective layer on the second surface of the semiconductorsubstrate; an insulating pattern on the antireflective layer and havingan opening; a color filter in the opening; a capping insulating layer onthe color filter and in the opening; a through hole passing through thesemiconductor substrate; a through electrode in the through hole; acontact plug passing through the insulating pattern and theantireflective layer and contacting the through electrode; a firstelectrode contacting the contact plug and overlapping the color filter;a separation structure contacting a side surface of the first electrode;and a photoelectric layer on the first electrode and the separationstructure, wherein the photoelectric layer includes a first portionoverlapping an upper surface of the first electrode adjacent to theseparation structure and a second portion overlapping an upper surfaceof the separation structure, and wherein a distance between the secondsurface of the semiconductor substrate and a lower surface of the firstportion of the photoelectric layer is different from a minimum distancebetween the second surface of the semiconductor substrate and a lowersurface of the second portion of the photoelectric layer.
 12. The imagesensor of claim 11, wherein the distance between the second surface ofthe semiconductor substrate and the lower surface of the first portionof the photoelectric layer is greater than the minimum distance betweenthe second surface of the semiconductor substrate and the lower surfaceof the second portion of the photoelectric layer.
 13. The image sensorof claim 11, wherein a maximum thickness of the first electrode isgreater than a minimum thickness of the separation structure.
 14. Theimage sensor of claim 11, wherein the separation structure includes afirst insulating layer and a second insulating layer on the firstinsulating layer, wherein the second insulating layer includes a firstside surface in contact with the first electrode and a second sidesurface opposing the first side surface, wherein a thickness of thesecond insulating layer adjacent to the first electrode is greater thana thickness of a center portion of the second insulating layer betweenthe first side surface of the second insulating layer and the secondside surface of the second insulating layer.
 15. The image sensor ofclaim 12, further comprising: a photodiode in the semiconductorsubstrate; and a second electrode on the photoelectric layer, whereinthe photoelectric layer and the second electrode overlap the firstelectrode and the separation structure, and wherein the photoelectriclayer is an organic photoelectric layer.
 16. An image sensor,comprising: a semiconductor substrate having a first surface and asecond surface opposing the first surface; a circuit interconnectionregion under the first surface of the semiconductor substrate; colorfilters on the second surface of the semiconductor substrate; aninsulating pattern on the second surface of the semiconductor substrate,wherein at least a portion of the insulation pattern is between thecolor filters; through holes passing through the semiconductorsubstrate; through electrodes in the through holes; contact plugspassing through the insulating pattern and contacting the throughelectrodes; first electrodes contacting the contact plugs andoverlapping the color filters; separation structure between the firstelectrodes; and a photoelectric layer on the first electrodes and theseparation structure, wherein the separation structure has a curvedupper surface extending from an upper surface of the first electrodes.17. The image sensor of claim 16, wherein the curved upper surface ofthe separation structure is a curved surface bent toward the secondsurface of the semiconductor substrate.
 18. The image sensor of claim16, wherein the separation structure includes a first insulating layerand a second insulating layer on the first insulating layer, and whereina side surface of the first insulating layer is aligned with a sidesurface of the second insulating layer.
 19. The image sensor of claim16, wherein the separation structure includes a first insulating layerand a second insulating layer on the first insulating layer, wherein thesecond insulating layer has the curved upper surface, and wherein thefirst insulating layer has a flattened upper surface.
 20. The imagesensor of claim 16, further comprising: a photodiode in thesemiconductor substrate; and a second electrode on the photoelectriclayer, wherein the photoelectric layer and the second electrode overlapthe first electrodes and the separation structure, and wherein thephotoelectric layer is an organic photoelectric layer.